As a technique for measuring a deformation (strain) of a measuring object, a technique has been known in which a metallic foil strain gauge is used by making use of the fact that a resistance value of the metallic foil changes by a strain. This is a technique, in which this strain gauge is adhered to the measuring object, and a length of the metallic foil is changed according to the strain of the measuring object, and as a result, and by detecting the changing resistance value of the metallic foil, the strain of the measuring object can be measured.
Further, since the resistance value of the metallic foil has a sensitivity not only for the strain but also for the temperature, as a technique for offsetting a measurement error caused by temperature change, a strain gauge in which a metallic foil resistor having sensitivity for strain and a wheatstone bridge circuit for performing temperature compensation is formed on the same substrate is disclosed in Japanese Patent Application Laid-Open Publication No. 07-270109 (Patent Document 1). Note that, in the following, the wheatstone bridge is referred to as a bridge.
Further, since the power consumption of these circuits is large, if they are battery-operated, there has been a problem that the battery runs out promptly. Hence, as disclosed in Japanese Patent Application Laid-Open Publication No. 2005-114443 (Patent Document 2), a technique in which a strain is detected from change in resistance value of a diffusion resistor of high resistance, formed on the semiconductor substrate using semiconductor manufacturing technique, is developed.